Alkylation of aromatic hydro-



Aug. 8, 1961 c. B. LlNN ErAL ALKYLATION oF ARoMATIc HYDRocARBoNs Filed Aprii s. 1959 Reacforl Frabf/'ona/or United States Patent O 2,995,611 ALKYLATION F AROMATIC HYDRO- v CARBONS Carl B. Linn, Riverside, and George L. I Iervert, Downers Grove, Ill., assignors to Universal Orl Products Company, Des Plaines, lll., a corporation of Delaware Filed Apr. 3, 1959, Ser. No. 803,932 11 Claims. (Cl. 260-671) This invention relates to a process for the alkylation of an aromatic hydrocarbon, and more particularly, relates to a process for the alkylation of an alkylatable benzene hydrocarbon with anoleiin-acting compound, and still .more particularly, relates to the alkylation of benzene with ethylene and/ or propylene in combination with unreactive gases. Further, this invention relates to a combination process including the steps of alkylation, gasliquid separation, fractionation, countercurrent gas-liquid absorption, and selective alkyl transfer.

An object of this invention is to produce alkyl-aromatic hydrocarbons, and more particularly, to produce alkylated benzene hydrocarbons. A specific object of this invention is to produce ethylbenzene, a desired chemical intermediate, which ethylbenzene is utilized in large quantities in dehydrogenation processes for the manufacture of styrene, one of the starting materials for the production of some synthetic rubber. Another speciiic object of this invention 4is to produce alkylated aromatic hydrocarbons boiling within the gasoline boiling range having high antiknock value and which may be used as such or as a oomponent of gasoline suitable for use in automobile and airplane engines. A further speciiic object is a process for the production of cumene by the reaction of benzene with propylene, which cumene product is oxidized in large quantities to form cumene hydroperoxide which is readily decomposed into phenol and acetone. Another object of this invention is to provide a process for the introduction of alkyl groups into aromatic hydrocarbons of high vapor pressure at normal conditions with minimum loss of said high vapor pressure aromatic hydrocarbons and maximum utilization thereof in the process. Still another object of this invention is a process in which molar excesses of aromatic hydrocarbons to be alkylated are utilized, and in which process the yield of mono-alkylated aromatic product is exceptionally high due to maximum util-ization of polyalkylated aromatic hydrocarbon byproducts. 'I'he further object of maximum boron trifluo ride utilization as a catalyst in this process, along with the other objects of this invention, will be set forth hereinafter as part of the accompanying specification.

In prior art processes forA the alkylation of aromatic hydrocarbons with olefin hydrocarbons, it has been disclosed that it is preferable to utilize molar excesses of such aromatic hydrocarbons. In such processes, it -is generally preferable to utilize greater than two mols of Y aromatic hydrocarbon per mol of olefin hydrocarbon and in many cases, for best reaction, it is preferred to utilize three or more mols of aromatic hydrocarbon per mol of olefin hydrocarbon. This has been found necessary to prevent polymerization of the olefin hydrocarbon from taking place prior to the reaction of the oleiin hydrocarbon with the aromatic hydrocarbon. Further, it has been found advantageous for maximum olefin utilization in the process. Due to the eiect of the law of mass action, one might .expect that the yield of polyalkylated aromatic ICC ' hydrocarbons which results therefrom would be minimized. While this is generally true, substantial yields of polyalkylated aromatic hydrocarbons are generally formed even when utilizing such molar excesses of aro'- matic hydrocarbon reactant. The formation of these polyalkylated aromatic hydrocarbons naturally increases the consumption of aromatic hydrocarbon in the process based on the yield of desired alkylated aromatic hydrocarbon. 'Ihis is an-obvious economic disadvantage since one seeks to achieve not only maximum oleiin-acting compound consumption in the process, but also maximum utilization of aromatic hydrocarbon to desired product. A further problem arises when these molar excesses of aromatic hydrocarbon to be alkylated are utilized in connection with the alkylation of aromatic hydrocarbons of high vapor pressure at normal conditions, particularly when the olefin hydrocarbon utilized as the olefin-acting compound or alkylating agent is a normally gaseous olefin hydrocarbon such as ethylene, propylene,'1butene, 2- butene, or isobutylene, and this problem is further accentuated when this alkylation is carried out in the presence of a gaseous acidic catalyst such as exempliiied by boron triuoride. The above mentioned olefin hydrocarbons are often present as minor quantities in various refinery gas streams containing major quantities of other gases -such as hydrogen,`nitrogen, hydrogen sulfide, and hydro carbons such as methane, ethane, propane, n-butane, and isobutanc. It has become very desirable to utilize such gas streams for their olefin content and a problem has arisen therewith which is particularly peculiar t0 the utilization of a gaseous acidic catalyst such as boron triuoride. By utilization of the process of the present invention, these problems can be solved with maximum yield of desired alkylated aromatic hydrocarbon and minimum loss vof oleiin-acting compound, alkylatable aromatic hydrocarbon, and gaseous acidic catalyst.

One embodiment of the present invention relates to a process for the production of an alkyl aromatic hydrocarbon which comprises passing to a first alkylation reaction zone containing a boron triuoride modified substantially anhydrous inorganic oxide, olefin-acting compound, alkylatable -aromatic hydrocarbon -in a molar quantity in excess of said olefin-acting compound, etliuents from a second transalkylation reaction zone produced as hereinafter set forth, and not more than 0.8 gram of boron triuoridc per gram mol of olefinacting compound, reacting therein said alkylatable aromatic hydrocarbon with said olefin-acting compound at alkylation conditions in the presence of an alkylation catalyst cornprising said boron triuoride modified inorganic oxide, separating from eiuents of the first alkylation reaction zone excess alkylatable aromatic hydrocarbon, desired alkylated aromatic hydrocarbon, and higher molecular weight polyalkylated aromatic hydrocarbon, recycling at least a portion ofthe excess alkylatable aromatic hy drocarbon to the first reaction zone, removing desired alkylated aromatic hydrocarbon as product from the process, passing higher molecular weight polyalkylated aromatic hydrocarbon, alkylatable aromatic hydrocarbon and from about 0.002 gram to about 1.2 grams of boron trifluoride per gram mol of polyalkylated aromatic hydrocarbon to a second transalkylation reaction zone containing a boron tritluoride modied substantially anhydrous inorganic oxide, reacting therein said alkylatable aromatic hydrocarbon with said higher molecular weight polyalkyl- 3 ated aromatic hydrocarbon at transalkylation conditions in the presence of a transalkylation catalyst comprising said boron triuoride and boron triuoride modified inorganic oxide, and recycling the emuents from said second transalkylation reaction zone to the 'first alkylation zone as aforesaid.

Another embodiment of the present invention relates to a process for the production of an alkyl aromatic hydrocarbon which comprises passing to a Iirst alkylation reaction zone containing a boron trifiuoride modified substantially anhydrous gamma alumina, olefin, alkylatable aromatic hydrocarbon in a molar quantity in excess of said olefin, eiuents from a second trans-alkylation reaction zone4 produced as hereinafter s et forth, and from about 0.001 gram to about 0.8 gram of boron triffuoride per gram mol of olefin, reacting rtherein said alkylatable aromatic hydrocarbon with said olefin at alkylation conditions in the presence of an alkylation catalyst comprising said boron triuoride and boron trifluoride modified substantially anhydrous gamma alumina, separating from emuents of the rst alkylation reaction -zone excess alkylatable aromatic hydrocarbon, desired alkylated aromatic hydrocarbon, and higher molecular weight polyalkylated aromatic hydrocarbon, recycling at least a portion ofthe excess alkylatable aromatic hydrocarbon to the first reaction zone, removing desired alkylated aromatic hydrocarbon as product from the process, passing higher molecular weight polyalkylated aromatic hydrocarbon, alkylatable aromatic hydrocarbon, and from about 0.002 gram to about 1.2 gram of boron trifiuoride per gram mol of polyalkylated aromaticvhydrocarbon to a second transalkylation reaction zone containing a boron triuoride modied substantially anhydrous gamma alumina, reacting therein said alkylatable aromatic hydrocarbon with said higher molecular weight polyalkylated aromatic hydrocarbon at ltransalkylation conditions in the presence of a transalkylation catalyst comprising said boron triliuoride and boron triffuoride modified substantially anhydrous gamma alumina, and recycling effluents from said second transalkylation reaction zone to the first alkylation reaction zone as aforesaid.

A further embodiment ofthe present invention relates to a process for the production of an alkyl benzene hydrocarbon which comprises passing to a iirst alkylation reaction zone containing a borontriuoride modified substantially anhydrous gamma alumina, normally gaseous olefin, alkylatable benzene hydrocarbon in a molar quantity in excess of said olefin, eiuents from a second transalkylation reaction zone produced as hereinafter set forth, and from about 0.001 gram to about 0.8 gram of boron triiiuonde per gram mol of normally gaseous olefin, reacting therein said alkylatable benzene hydrocarbon with said normally gaseous olefin at alkylation conditions in the presence of an alkylation catalyst comprising said boron triuoride and boron tn'uoride modified substantially anhydrous gamma alumina, separating from efiiuents of the irst'alkylation reaction zone excess alkylatable benzene hydrocarbon, desired alkylated benzene hydrocarbon, `and higher molecular weight polyalkylated benzene hydrocarbon, recycling at least a portion of the excess alkylatable benzene hydrocarbon to the iirst reaction zone, removing desired alkylated benzene hydrocarbon as product from the process, passing higher molecular weight polyalkylated benzene hydrocarbon, alkylatable benzene hydrocarbon, and from about 0.002 gram to about 1.2 grams of boron trifiuoride per gram mol of polyalkylated benzene hydrocarbon to a lsecond transalkylation reaction zone containing a boron tritluoride modified substantially anhydrous gamma alumina, reacting therein said alkylatable benzene hydrocarbon with saidhigher molecular weight polyalkylated benzene hydrocarbon at transalkylation conditions in the presence of a transalkylation cat- 4 reaction zone tothe first alkylation reaction zone as aforesaid.

A specic embodiment of the present invention relates to a process for the production of ethylbenzene which comprises passing to a first alkylation reaction zone containing a boron triuoride modied substantially anhydrous gamma alumina, ethylene, benzene in a molar quantity in excess of said ethylene, efiluents from a second transalkylation reaction zone produced as hereinafter set forth, and from about 0.001 gram to about 0.8 gram of boron triuoride per gram mol of ethylene, reactingv therein said benzene with said ethylene at a temperature of from about 0 to about 300 C. and at a pressure of from about atmospheric to about 200 atmospheres inthe presence of an alkylation-catal-yst comprising said boron triuolide and boron triiluoride modified substantially anhydrous gamma alumina, separating from efiiuents of the first alkylation reaction zone excess benzene, ethylbenzene, and polyethyl-ated benzene, recycling at least a portion of the excess benzene ato the first reaction zone, removing desired ethylbenzene yas product from the process, passing higher molecular Weight polyethylated benzene, benzene and fromabout 0.002 gram to about 1.2 grams of boron triuoride per gram mol of polyethylated benzene to a second transalkylation reaction zonerco'rntaining aboron tritiuoride modified substantially anhydrous lgamma alumina, reacting therein said benzene with said polyethylated benzene at a temperature of from about 150 to about 350 C. and a pressure of from about atmospheric to about 200 atmospheres in the presence of a transalkylation catalyst comprising said boron trifiuoride an-d boron triuoride modified Substantially anhydrous gamma alumina, and recycling eiuents from said second transalkylation reaction zone to the irst alkylation reaction zone as aforesaid.

Another specific embodiment of the present invention relates to a process for the production of cumene which comprises passing to a first alkylation reaction zone con-v taining a boron trifiuoride modified substantially anhydrous gam-ma alumina, propylene, benzene in a molar quantity in excess of said propylene, efliuents from a second transalkylation lreaction zoneV produced as herein-l after set forth, and from about'0.00l gram to about 0.8

gram of boron tritiuoride per gram mol of propylene,v

reacting therein said -benzene with saidV propylene at a temperature of from about 0 to about 300 C. and

' at a pressure of from about atmospherieto about 200 alyst comprising said boron Vtriiiuoride and boron tri- Y and recycling efuents from said second transalkylation atmospheres in the presence of an alkylation catalyst comf prxsmg sald boron tritiuoride and boron triffuoride modified substantially anhydrous gamma alumina, separating lfrom efiiuents of the first alkylation reaction zone excess benzene, cumene, and polypropylated benzene, recycling at least a portion of the excess benzene to the first reacf tion zone, removing desired cumene as product from the anhydrous gamma alu-mina, reacting therein said benzene with said polypropylated benzene ata temperature -ofV from about V to about 350 C. and a pressure of from about atmospheric to about 200 atmospheres in the presence of a transalkylation catalyst comprising saidV boron trifiuoride and boron trifiuoride modified substanl tially anhydrous gamma alumina, and recycling etliuents from said second transalkylation reaction zone to the first alkylation reaction zone as aforesaid.

This invention can be most clearly described and illustrated with reference to the attached drawing. While` of necessity, certainlimitations must be present inY suchgaV schematic description, no intention is meant thereby'to limit the generally broad scope of this invention. VAs stated hereinabove, the rst step of the process of the present invention comprises alkylating an alkylatable aromatic hydrocarbon with an olefin-acting compound at aikylation conditions in the presence of an alkylation catalyst comprising a boron trifluoride modied inorganiccxide. In the drawing, this first step is represented as taking place in reaction zone 7. However, the mixture of alkylatable aromatic hydrocarbon, olefin-acting compound, and make-up boron trifluoride, when necessary, must be furnished to this reaction zone. In the drawing, the olefin-acting compound -is represented as being furnished to reaction zone 7 through line 5 containing pressure control valve 6. The alkylatable aromatic hydrocarbon is combined therewith in line 4 by passage through line 1 containing indirect heat exchange zone 2 and through line 3. Line 3 in the drawing also represents means through which excess alkylatable aromatic hydrocarbon, after being used as an absorber oil, is recycled to reaction zone 7. Line 3 in the drawing also represents means through which effluents containing boron triuoride from the hereinafter described transalkylation reaction zone are passed to reaction zone 7. Line 60 in the drawing represents means through which additional boron tritiuoride may be added to the first alkylation reaction zone, if necessary, although generally the boron trifluoride is added to the process solely in the transalkylation reaction zone, hereinafter described, in a quantity sufiicient for both reaction zones.

The olefin-acting compound, particularly olefin hydrocarbon, which may be charged to reaction zone 7 via line 5 containing pressure control valve 6 and via line 4 may be selected from diverse materials including monoolens, diolefins, polyolefins, acetylenic hydrocarbons, and also alcohols, ethers, and esters, the latter including alkyl halides, alkyl sulfates, alkyl phosphates, and various esters of carboxylic acids. The preferred olefin-acting compounds are oleiinic hydrocarbons which comprisesfmonoolefins containing one double bond per molecule and polyolefins which contain more than one double bond per molecule. Monoolefins which are utilized as olefin-acting compounds in the process of the present invention are either normally gaseous or normally liquid and include ethylene, propylene, l-butene, 2butene, isobutylene, and higher molecular weight normally liquid olefins such as the various pentenes, hexenes, heptenes, octenes, and mixtures thereof, and still higher molecular weight liquid olefins, the latter including various olefin polymers having from about 9 to about 18 carbon atoms per molecule including propylene trimcr, propylene tetra-mer, propylene pentamer, etc. i Cycloolefins such as cyclopentene, methylcyclopentene, cyclohexene, methylcyclohexene, etc., may also be utilized. Also included within the scope of the term olefin-acting compound are certain substances capable of producing olefinic hydrocarbons or intermediates thereof under the conditions of operation utilized in the process. Typical 'olefin-producing substances or olefin-acting compounds capable of use include alkyl halides capable of undergoing dehydrohalogenation to form olenic hydrocarbons and thus containing at least two carbon atoms per molecule. Examples of such alkyl halides include ethyl uoride, n-propyl fluoride, isopropyl fluoride, n-butyl uoride, isobutyl fluoride, sec-butyl fluoride, tert-butyl fluoride, etc., ethyl chloride, n-propyl chloride, isopropyl chloride, n-butyl chloride, isobutyl chloride, sec-butyl'chloride, tert-butyl chloride, etc., ethyl romide, n-propyl bromide, isopropyl bromide, n-butyl bromide, isobutyl bromide, sec-butyl bromide, tert-butyl bromide, etc. As stated hereinabove, other esters such as alkyl sul-fates including ethyl sulfate, propyl sulfate, etc., and alkyl phosphates including ethyl phosphate, ets., may be utilized. Ethers such as diethyl ether, ethylpropyl ether, dipropyl ether, etc., are also yincluded withm the generally broad scope of the term olefin-acting compound and may be successfully utilized as alkylating agents in the process of this invention.

Olelin hydrocarbons, particularly normally gaseous olefin hydrocarbons, are preferred olefin-acting cornpounds for use in the process of this invention and for passage by means of lines 5 and 4 to reaction zone 7. The process of this invention may be successfully applied to and utilized for. complete conversion of olefin hydrocarbons when these olen hydrocarbons are present in minor quantities in various gas streams. Thus, in contrast to prior art processes, the normally gaseous olefin for use in the process of this invention need not be concentrated. Such normally gaseous olefin hydrocarbons appear in minor quantities in various refinery gas streams, usually diluted with various gases such as hydrogen, nitrogen, methane, ethane, propane, etc. These gas streams containing minor quantities of olefin hydrocarbons are obtained in petroleum refineries from various refinery installations including thermal cracking units, catalytic cracking units, 'thermal reforming units, coking units, polymerization units, etc. Such refinery gas streams have in the past often been burned for fuel value since an economical process for the utilization of vtheir olefin hydrocarbon content has not been available, or processes which have been suggested by the prior art utilize such -large quantities of a1- kylatable aromatic hydrocarbon that they have not been economically feasible. This is particularly true for refinery gas streams known as off-gas streams containing relatively minor quantities of olefin hydrocarbons such as ethylene. Thus, it has been possible to catalytically polymerize propylene and/or butenes in various renery gas streams, but the ofi-gases from such processes still contain the utilizable olefin hydrocarbon, ethylene. Prior to our invention, it has been considered necessary to concentrate this ethylene for use as an alkylating agent or olefin-acting compound. In addition to containing Yethylene in minor quantities, these off-gas streams contain other olefin hydrocarbons, depending upon their source, including propylene and butenes. A refinery off-gas stream may contain varying quantities of hydrogen, nitrogen, methane, and ethane with the ethylene in minor proportion, while a refinery off-gas propylene stream is normally diluted with propane and contains the propylene in minor quantity, and a refinery off-gas butene stream is normally diluted with butanes and contains the butenes in minor quantities. A typical analysis in mol percent for a utilizable refinery ofi-gas from a catalytic cracking unit is .as follows: nitrogen, 4.0%; carbon monoxide, 0.2%;v hydrogen, 5.4%; methane, 37.8%; ethylene, 10.3%; ethane, 24.7%; propylene, 6.4%; propane, 10.7%; and C4 hydrocarbons, 0.5%. It is readily observed that the total olefin content of this gas stream is 16.7 mol percent and the ethylene content is even lower, namely 10.3 mol percent. Such gas streams containing olefin hydrocarbons in minor or dilute quantities are particularly preferred olefin-acting compounds within the broad scope of theinvention. It is readilyl apparent that only the olefin content of such streams undergoes reaction at alkylation conditions in the process of this invention, and that the remaining gases -free from 'olefin hydrocarbons are vented from the process. It is one of the features of this invention that the non-reactive gases are vented from the process with minimum loss of boron triuoride and alkylatable aromatic hydrocarbons due to their vapor pressure at the conditions of temperature and pressure utilized for venting the lnon-reactive gases.

The olefin-acting compound or normally gaseous oletin hydrocarbon has combined therewith in line 4 a1- `kylatable aromatic hydrocarbon from line 3 which may but usually does not have boron triiiuoride combined vtherewith from line 60 as will be set forth further hereinafter. Many aromatic hydrocarbons are utilizable as alkylatable aromatic hydrocarbons within the process of this invention. Preferred aromatic hydrocarbons 7 are monocyclicaromatic hydrocarbons, that is, benzene hydrocarbons. Suitable aromatic hydrocarbons include benzene, toluene, ortho-xylene, meta-xylene, para-xy-y of aromatic hydrocarbons with olefin polymers. Such atable aromaticv hydrocarbon absorber oil is -ava11ab1e 1 in the process since it is preferred to utilize a molar' products are referred to in the art as alkylate, and in-v clude hexylbenzene, hexyltoluene, nonylbenzene, nony1` toluene, dodecylbenzene, dodecyltoluene, pentadecylbenzene, pentadecyltoluene, etc, Other suitable alkylatable Y aromatic hydrocarbons include those with two or more aryl groups such as dphenyl, diphenylmethane, triphenylmethane, iluorene, stlbene, etc. Examples of alkylatable aromatic hydrocarbons within the scope of this invention utilizable as starting materials and containing condensed benzene rings include naphthalene, alpha-y methylnaphthalene, beta-methylnaphthalene, etc.,v anthracene, phenanthrene, naphthacene, rubrene, etc. l When the selected alkylatable aromatic hydrocarbonis a solid, it maybe heated by means not shown so that 1t passes as a liquid through line 1 or line 28 as hereinafter described. Of the above alkylatable aromatic hyasoman the alkylation reaction zone inthe efiluents from the transalkylation zone wherein the boronvtrifluoride, has acted as the catalyst, and thus one in effect obtains double usage o f this small amountk of boron trilluoride in the combined process. y

Prior to entry from line 4 to reaction zone 7, the reactants andcatalyst, if any, have combined therewith recycle alkylatable aromatic hydrocarbon absorber oil containing boron triuoride via'line 59 and transalkylation reaction .zone efuentvia line 3. Recycle alkylexcess of alkylatable aromatic hydrocarbon over olenacting compound, preferably olefin. This, as is disclosed in the prior art, has been found necessary to prevent side reactions from .taking place, such as, for ex-` ample, polymerization of the olefin-acting compound prior to reaction thereof with the alkylatable aromatic hydrocarbon, and to direct the reaction principallyto monoalkylation. The excess alkylatable aromatic hydrocarbon, as will be described hereinafter, is a useful absorber oil to prevent loss of gaseous alkylatable aromatic hydrocarbon in"V the gas stream vented from the drocarbons for use as starting materials in the process of this invention, the benzene hydrocarbons are preferred, and of the benzene hydrocarbons, benzene itself is particularly' preferred.

As stated hereinabove, when desired, boron triuoride I may be added in admixture with the alkylatable aromatic hydrocarbon prior to passage thereof to line 4. Generally, the boron trifluoride addition to the process is through line 51, as set forth hereinafter, so that bo'- ron trilluoride addition at this point is not necessary. When desired, this is accomplished by passage of the process. Furthermore, the alkylatable aromatic hydrocarbon dissolves boron triuoride from the eluent unreactive gases and its -use in this manner permits a unitary combination process in which only minor quantities or no boron triuoride addition is necessary to maintain catalyst activity and desired reaction.

The combined feed to the reaction zone comprising alkylatable aromatic hydrocarbon in a molar excess based on olefin-acting compound, olefin-acting compound, effluents froml a second transalkylation reaction zone produced as hereinafter set forth, and boron triiiuoride provided in the manner hereinabove specified is passed to reaction zone 7. lReaction zone 7 is of the conventional type and may be equipped with heat transv fer means, baffles, trays,meta1 packing, heating means,

boron trifluoride from line 60 through line 3. Boron triuoride is a gas, boiling point -101 C., melting point 126 C., and is somewhat soluble in most organic solvents. It may be and generally is utilized per se by mere passage thereof as a gas through lines 60 and 3 under sufficient pressure so that it dissolves at least partially in the alkylatable aromatic hydrocarbon passing concurrently therewith through line 3. The boron triuoride may also be added as a solution of the gas in a suitable organic solvent. However, in the utilization of such solutions, care must be exercised so that the selected solvent is unreactive with the olefin-acting compound or normally gaseous olefin hydrocarbon utilized in the process. Furthermore, boron triuoride complexes with many organic compounds, particularly those containing sulfur or oxygen atoms. These complexes, while utilizable as catalysts, are very stable and thus will interfere with the recovery of boron triliuoride in the gas-liquid absorption zone hereinafter set forth. Therefore, a further limitation upon the selection of such a solvent is that it be free from atoms or groups which form complexes with boron trifluoride. Gaseous borontriuoride itself is the preferred catalyst.

' The amount of boron trifluoride which is utilized is relatively small. It has been found that the amount necessary can beconveniently expressed as grams of boron triuoride per gram mol of olefin-acting compound, preferably olefin. This amount of boron triuoride will range `from about 0.-1 milligram to `about 0.8V gram of boron trilluoride per gram mol of olefin utilized. When the amount of boron triuoride present in the reaction zone is within the above expressed range, substantially complete conversion of the olefin-acting vcompound is obtained, even when the olefin-acting compound is present in what might seem to be minor or dilute quantities in a gas stream. In the preferred embodiment of this process, this amount of boron trifluoride is furnished to etc. The reaction zone preferably is of the adiabatic type and thus the feed to this zone will preferably be provided with the requisite amount of heat prior to passage thereof to said zone. In a preferred embodiment, this reaction zone will be adiabatic and packed with a refractory oxide. The refractory oxide with which said zone is packed may be selected from among various inorganic oxides including alumina, slica, boria, oxides of phosphorus.(which for thepurposes'of this specification along with the silica are considered to be metal oxides), titanium dioxides, zirconium dioxide, chromia, zinc oxide, magnesia, calcium oxide, silica-alumina, silica-magnesia', silicaalumina-magnesia, silica-aluminazirconia, chromia-alumina, alumina-boria, silica-zirconia, etc., and various naturally occurring inorganic oxides of various states ofV purity such as bauxite, clay (which may or may not have been 'previously acid treated), diatomaceous earth, etc. Of the above mentioned inorganic oxides for use as packing in reaction zone 7, alumina is preferred.

The conditions utilized in reaction zone 7 may be varied over a relatively wide range. Thus, the desired alkylation reaction in the presence of the above indicated boron triuoride catalyst may be effected at a temperature of from about 0 C. or lower tov about 300 C. orV Y aromatic hydrocarbon in substantially liquid phase.

Within the above mentioned temperature and pressure ranges, it is not always possible to maintain the olefinacting compound in liquid phase. Thus, when utilizing a refinery off-gas containing ethylene as theoleln-acting v compound, the ethylene will` be dissolved in the liquid phasev alkylatable aromatic hydrocarbon (and alkylated The pressure aromatic hydrocarbon as formed) to the extent governed by temperature, pressure, and solubility considerations. However, a portion thereof will always be in the gas phase. Referring to the aromatic hydrocarbon to be alkylated, it is preferable to have present lfrom about 2 up to about 10 or more, sometimes up to 2O molar proportions per molar proportion of olefin-acting compound introduced therewith. The hourly liquid space velocity of the liquid through the reaction zone may be varied over a relatively wide range of from about 0.1 to about 20 or more.

When the alkylation reaction has proceeded to the desired extent, the products from the alkylation zone, which may be termed alkylation zone eiuent, are withdrawn from zone 7 through line 8, are indirectly heat exchanged in heat exchanger 2 with fresh alkylatable aromatic hydrocarbon, and are passed through line 9 to separator 10, also known as the alkylation reaction zone eflluent receiver. The alkylation or reaction zone euent which passes into separation zone 10 comprises unreactive gases, if any, which were introduced to the system along with the olefin-acting compound, boron triiluoride, excess alkylatable aromatic hydrocarbon, alkylated aromatic hydrocarbon, and polyalkylated aromatic hydrocarbon. The unreactive gases, if any, and the boron triiuoride are separated as gases in gas-liquid separation zone 10, and passed through line 11 containing pressure control valve 12 to gas-liquid absorption zone 56, hereinafter described. Since the alkylatable aromatic hydrocarbon was utilized in excess in the reaction zone, the excess alkylatable aro matie hydrocarbon will be present in separation zone 10 and a portion thereof will be vaporized overhead due to its vapor pressure at these conditions along with the unreactive gases and boron trifluoride. The temperature of separation zone 10 will be less than that of the reaction zone in most cases, due to the cooling which has taken place in heat exchanger 2 by indirect heat exchange with fresh alkylatable aromatic hydrocarbon. 'Ihe liquid which is separated in separation zone 10 passes therefrom through line 13 containing liquid level control valve 14 to the iirst fractionation zone 15.

Fractionation zone 15 is a conventional fractional distillation column or tower and is utilized for the purpose of recovering excess unreacted alkylatable aromatic hydrocarbon from the reaction zone eflluents for use as absorber oil and recycle. The recovered unreacted alkylatable aromatic hydrocarbon passes overhead from fractionation zone 1 5 through line 16 containing condenser 17 to overhead receiver 18. Overhead receiver 16 is equipped with gas take-off means, shown on the drawing as line 19, which serves to remove any gases which have failed to be removed by means of gas-liquid separation zone 10. This amount is, of course, very small. These gases pass from overhead receiver 18 through line 19, are compressed by compressor 20, and are combined with the gases from line 11. Both of these gas streams pass through line 57 to gas-liquid absorption zone 56, hereinafter described. The unreacted alkylatable aromatic hydrocarbon recovered overhead from fractionation zone 15 is withdrawn from overhead receiver 18 through line 21 by pump 22 which provides recycle to fractionation zone 15 by means of lines 23 and 24 and which also recycles the remainder or net amount of the recovered alkylatable aromatic hydrocarbon via lines 25 and 26 to gas-liquid absorption zone 56. After use therein of the excess alkylatable aromatic hydrocarbon as absorber oil, this excess alkylatable aromatic hydrocarbon passes back to reaction zone 7. If desired, a portion of the thus recovered excess alkylatable -aromatic hydrocarbon may be passed via lines 27 and 29 to the transalkylation reaction zone hereinafter described. The flow of this alkylatable aromatic hydrocarbon in this direct-ion is controlled by valve 61 in line 27. Generally, this valve is maintained in a closed position. However, in some 10 matic hydrocarbon are utilized in reaction zone 7, it will be possible to supply the desired amount of alkylatable aromatic hydrocarbon for use in the transalkylation reaction zone by this means. In such a case, no fresh alkylatable aromatic hydrocarbon would be added to the process through line 28, the net input of such hydrocarbon being added via line 1. In an equivalent operation,

the net input of alkylatable aromatic hydrocarbon may be added via line 28 and none added through line 1 thus maintaining the process in balance. Referring back again to fractionation zone 15, the higher boiling alkylated aromatic hydrocarbons are withdrawn therefrom by means of lline 30 and passed therethrough to a second fractionation zone 31. The requisite amount of heat is furnished to fractionation zone 15 by a heating coil as shown in the drawing, or by other means such as a reboiler not shown.

Gas-liquid absorption zone 56 is a countercurrent contacting zone, of conventional design, the size of which is varied depending upon the quantity of recycle alkylatable aromatic hydrocarbons passed thereto and upon the quantity of unreacted aromatic hydrocarbon, boron trifluoride, and unreactive gases passed to a lower region thereof. In gas-liquid absorption zone 61, the alkylatable aromatic hydrocarbons from overhead receiver- 18 pass into an upper region thereof through line 26 and ow downward in a countercurrent manner to the gases which are introduced thereto in a lower region thereof, for example, via line 57. The unreacted alkylatable aromatic hydrocarbon vaporized in separation zone 10 and boron triuoride are recovered and dissolved in the cooler excess alkylatable aromatic hydrocarbon. 'I'he unreactive gases are vented from -absorption zone 56 through line 58 as shown. The excess alkylatable aromatic hydrocarbon and boron trifluoride is withdrawn from the bottom of gas-liquid absorption zone 56 through line 59 and recycled to reaction zone 7 through line 3 as hereinabove set forth.

Second fractionation zone 31 is of the conventional type and is utilized for recovery of desired alkylated aromatic hydrocarbon from higher boiling homologs thereof. 'I'he desired alkylated aromatic hydrocarbon is withdrawn overhead from fractionation zone 31 through line 32 containing condenser 33 and is passed to overhead receiver 34. The liquid product from overhead receiver 34 comprises desired alkylated aromatic hydrocarbon which is withdrawn therefrom through line 35 by pump 36 which provides reflux to fractionation zone 31 by means of lines 37 and 38. Pump 36 also provides -a means for passage of the desired alkylated aromatic hydrocarbon from the process by means of line 39. As will be set forth further in the example, the desired alkylated aromatic hydrocarbon may be a pure compound such as ethylbenzene, or a mixture of monoalkylated aromatic hydrocarbons such as ethylbenzene and cumene, or other mixtures which may be passed to further fractionation means not shown for separation of the desired individual components therefrom. The still higher boiling alkylated laromatic hydrocarbons are withdrawn from fractionation zone 31 by means of line 40 and are passed to third fractionation zone 41. Fractionation zone 31 is heated by conventional means such as the heating coil shown in the drawing, although other means such as a reboiler not shown may be utilized for furnishing the requisite amount of heat thereto.

As stated hereinabove, the higher boiling alkylated aromatic hydrocarbons, in the preferred embodiment of this invention, are withdrawn from fractionation zione 31 through line 40 and passed to third fractionation zone 41. However, these higher boiling polyalkylated aromatic hydrocarbons may be withdrawn from fractionation zone 31 through line 40 and passed directly by means not shown through lines 29, 50 and 52 to the transalkylation reaction zone 54. This, of course, is a broad embodiment of the present invention and is utilized when no recases when relatively large amounts of alkylatable aro 75 running of the higher boiling Vpolyalkylated aromatic zone 41 is a conventional fractional distillation column and is utilized to rerun higher boiling alkylated hy r carbons. The higher boiling alkylated hydrocarbons are passed overhead therefrom through line 42, condensed in heat exchanger 43, and are passed to overhead receiver 44. From overhead receiver 44, these higher boiling alkylated aromatic hydrocarbons are withdrawn through line 45 by means of pump 46 which provides reux to fractionation zone 41 through lines 47 and 48. The net higher boiling polyalkylated aromatic hydrocarbons removed overhead are passed through lines 49, 50 and 52 to transalkylation reaction zone 54. The bottoms from the process are withdrawn from the bottom tion zone 41 through line 55. v

Prior to passage of the higher boiling polyalkylated Varomatic hydrocarbons from overhead receiver 44 to Ytransalkylation reaction zone 54, these hydrocarbons have combined therewith alkylatable aromatic hydrocarbon via line 28 or 27, as the case may be, to provide a molar excess thereof in relation to the alkyl groups contained in the polyalkylated aromatic hydrocarbons passed to said transalkylation reaction zone. Furthermore, a

' quantity of boron triuon'de in the amount of from about Vline 52, heated by means of heat exchanger 53 and passed to transalkylation reaction zone 54.

VTransalkylation reaction zone 54 is of the conventional type and may be equipped with heat transfer means, baflles, trays, metal packing, heating means, etc. The reaction zone preferably is of the adiabatic type and thus the feed to this zone will preferably -be provided'with the requisite amount of heat prior to passage thereof to said zone. In a preferred embodiment, this reaction zone will be adiabatic and packed with a refractory oxide. The

` refractory oxide with which said zone is packed may be selected from among various inorganic oxides including alumina, silica, boria, oxides of phosphorus, titanium dioxide, zirconium dioxide, chromia, zinc oxide, magnesia, calcium oxide, silica-alumina, silica-magnesia, silica-alumina-magnesia, silica-alumna-zirconia, chromiaalumina, alumina-boria, silica-zirconia, etc., and various naturally occurring inorganic oxides of various states of purity such as bauxite, clay (which may or may not have been previously acid treated), diatomaceous earth, etc. Of the above mentioned inorganic oxides for use as packing in reaction zone 54, alumina i's preferred.

The conditions utilized in reaction zone 54 may be varied over a relatively wide range, but are usually of greater severity than prevail in reaction zone 7 as set forth hereinabove. Thus, the concentration of boron trifluoride utilized thereinrwill be greater thanfor reaction zone 7, the temperature utilized may be higher, the hourly liquid spaccvelocity may be lower, or one or more of these means of increasing severity may be employed. Since the quantity of reactants passed to transalkylation reaction zone 54 is usually much less than passed to reaction zone 7, an easy means of increasing reaction zone severity is by proper control of the amount of boron triiluoride in relation to the polyalkylaromatic hydrocarbon. This quantity. of boron triuoride-then passesr from reaction zone 54 in the eluent therefrom and will be a sufficient lower quantity for use in reaction zone 7 with its larger quantity of reactants so that no additional boron trilluoride need be added thereto by means of line 60. Further, a combination of such boron "hydrocarbons is necessary and/or desired. Fractionation of fraetiona- 12 tn'uoride control and higher temperature is a preferred means for increasing reaction zone severity in zone 54.

As was the case with reaction zone 7, the conditions utilized in reaction zone l54 may be varied over a relatively Vwide range of said increased severity. Thus, the desired transalkylation yin the presence of the above indicated boron tritluoride catalyst may be effected at temperatures of from about 150 to about 350 C. or higher, preferably at a temperature of from about 175 C. to about 325 C. The transalkylation reaction is usually carried out at a pressure of from about substantially atmospheric to about 200 atmospheres. The pressure utilized is usually selected to maintain the alkylatable aromatic hydrocarbon and polyalkylated aromatic hydrocarbon in substantially liquid phase and to provide the necessary pressure for passage of the eiiiuent therefrom back to alkylation reaction zone 7 without the need for a pump. .Referring to the alkylatable aromatic compound, it is preferable to have present in the transalkylation rcation zone from greater than l to about 10 or more, sometimes up-to 20, molar proportions per molar proportion of -alkyl group in the polyalkylated aromatic hydrocarbon introduced therewith. The hourly liquid space velocity of the liquid thro'ugh transalkylation reaction zone 54 may be `varied over a relatively wide range of from about 0.25 to about 20 or more. When the transalkylation reaction has proceeded to the desired extent so that a suicient quantity of the polyalkylated aromatic hydrocarbons are converted to alkylated aromatic hydrocarbons by reaction with alkylatable aromatic hydrocarbon, the products from transalkylation zone 54, which may be termed transalkylation reaction zone eiiluent, are withdrawn through line 3 for recycle to reaction zone 7 as hereinabove described. Y

The following example is introduced for the purpose of illustration with no intention of Vunduly limiting the generally broad scope of this invention. This example illustrates the utilization of the process of the present invention for the simultaneous production of 532 barrels per day of ethylbenzene and 74 barrels per day of cumene. The catalyst utilized in the alkylation reaction zone comprises about 0.13 gram of boron tritluoride per gram mol of olefin in a reaction zone packed with gamma alumina. The catalyst utilized in the transalkylation reaction zone comprises about 0.25 gram of boron triuoride per gram mol of alkyl aromatic or about 0.13 gram of boron triuoride per gram mol of alkyl group present therein in a transalkylation reaction zone packed with gamma alumina. The example utilizes olf-gas from a catalytic cracking unit containing` both ethylene and propylene as olefin-acting compounds for reaction with benzene. The benzene to olefin ratio present in the reaction zone is about 9: 1. The production of the hereinabove described quantities of ethylbenzene and cumene are hereinafter described with reference to the attached drawing. Y

Referring to the drawing, olf-gas from a catalytic I cracking unit in the quantity of V6.14 X 10s standard cubic feet per day or 673.3 pound mols per hour, after compression, is fed to the plant through line 5 containing pressure control valve 6 set at 500 p.s.i.'g. These 673.3 pound mols per hour are made up as follows:l 89.4 mols of hydrogen, 71.9 mols of nitrogen, `4.4 mols of carbon monoxide, 268.2 mols of methane, 69.1 mols of ethylene, 154.7 mols of ethane, 10.1 mols-'of propylene, and 5.5 mols of propane. There is also charged to reactor 7, 7.4.0 pound mols per hour of fresh benzene through line 1, indirect heat exchanger 2, and lines 3 and 4. AlsoA charged to reactor 7 are 572.3 pound mols per hour of rich absorber oil and condensed separator vapors via lines 59, 3 and 4. This 572.3 pound mols per hour of rich absorber oil contains 0.05 mol of boron triluoride, 0.75 mol of methane, 9.45 mols of ethane, 1.72 mols of propane,.556.8 mols of benzene, and 3.56 mols of ethylbenzene. By means of lines 3 and 4 there is also charged to the reactor transalkylation reaction zone eluent con-` taining boron tritiuoride, benzene and alkylated benzenes, produced as hereinafter described, in the quantity of 104.5 pound mols per hour. This 104.5 pound mols per hour contains 0.1 mol of boron triuoride, 0.05 mol of methane, 0.95 mol of ethane, 0.18 mol of propane, 62.1 mols of benzene, 23.5 mols of ethylbenzene, 3.9 mols of cumene, 10.3 mols of diethylbenzenes, 2.6 mols of ethylcumene, and 0.8 mol of diisopropylbenzene. The combined feed is passed from line 4 to reactor 7 in the quantity of 1424.15 pound mols per hour. Reactor 7 is main-v tained at a temperature of 120 C., at a pressure of 500 p.s.i.g., with the reactants being passed therethrough at a liquid hourly space velocity of 0.75. I'he 1424.15 pound i mols per hour of combined feed passing to reactor 7 contains 0.15 mol of boron triuoride, 89.4 mols of hydrogen, 71.9 mols of nitrogen, 4.4 mols of carbon monoxide, 269.0 mols of methane, 69.1 mols of ethylene, 165.1 mols of ethane, 10.1 mols of propylene, 7.4 mols of propane, 692.9 mols of benzene, 27.1 mols of ethylbenzene, 3.9 mols of cumene, 10.3 mols of diethylbenzene, 2.6 mols of ethylcumene, and 0.8 mol of diisopropylbenzene. The benzene to olefin ratio is about 9:1.

In reactor 7 the olen content of the off-gas stream reacts with the benzene to form monoalkyl and polyalkyl benzene hydrocarbons. The reactor effluent passes from reaction zone 7 through line 8, is heat exchanged with fresh benzene in heat exchanger 2, and passes through line 9 to gas-liquid separation zone 10. This reactor eflvuent in the quantity of 1344.95 pound mols per hour contains 0.15 mol of boron uoride, 89.4 mols of hydrogen, 71.9 mols of nitrogen, 4.4 mols of carbon monoxide, 269.0 mols of methane, 165.1 mols of ethane, 7.4 mols of propane, 632.4 mols of benzene, 67.9 mols of ethylbenzene, 7.8 mols of cumene, 20.6 mols of diethylbenzene, 5.1 mols of ethylcumene, 1.5 mols of dipropylbenzene, 1.9 mols of diethylcumene, and 0.4 mol of triethylcumene. In separator 10 the gaseous products from the reaction zone etiiuent are separated from the liquid products. The gaseous products from the efliuent in the quantity of 565.8 pound mols per hour are passed from separator 10 through line 11 containing pressure control valve 12 and through line 57 to absorber 56, hereinafter described. 'Ihe liquid reaction zone euent passes from separator 10 through line 13 containing liquid level control valve 14 to fractionation zone 15, called the benzene column.

The benzene column 1S is fed with 779.16 pound mols per hour of separated liquid. This 779.16 pound mols per hour contains 0.06 mol of boron triuoride, 1.0 mol of nitrogen, 6.7 mols of methane, 35.5 mols of ethane, 4.0 mols of propane, 626.7 mols of benzene, 67.9 mols of ethylbenzene, 7.8 mols of cumene, 20.6 mols of diethylbenzene, 5.1 mols of ethylcumene, 1.5 mols of diisopropylbenzene, 1.9 mols of diethylcumene, and 0.4 mol of triethylcumene. In this benzene column 15, benzene and lower boiling materials are separated from the remaining liquid. Thus, there is passed overhead from column 15 through line 16 containing condenser 17 to overhead receiver 18 maintained at 100 F., 677.96 pound mols per hour containing 0.06 mol of boron trifluoride, 1.0 mol of nitrogen, 6.7 mols of methane, 35.5 mols of ethane, 4.0 mols of propane, 626.7 mols of benzene, and 4.0 mols of ethylbenzene. From receiver 18 there is recycled 42.66 pound mols per hour of gas through line 19 and compressor 20 which compresses this gas and passes the same through line 57 to gas-liquid absorption zone 56 hereinafter described. This 42.66 pound mols per hour of gas contains 0.06 mol of boron triuoride, 1.0 mol of nitrogen, 6.3 mols of methane, 27.5 mols of ethane, 2.5 mols of propane,and 5.3 mols of benzene.

The liquid in benzene column receiver18 is withdrawn therefrom through line 21 by pump 22 which discharges through line 23 and supplies reflux to benzene column 15 llines 26 and 27. The major proportion of this recycle benzene is passed through line 26 to gas-liquid absorption zone 56. A rninor proportion of this benzene passes through lines 27 and 29 to the transalkylation zone, this passage being controlled by the open position of valve 6l. In this manner there is passed to gas-liquid absorption zone 56, 558.08 pound mols per hour made up as follows: 0.35 mol of methane, 7.05 mols of ethane, 1.32 -mols of propane, 545.8 mols of benzene, and 3.56 mols of ethylbenzene. In a like manner, there is passed to transalkylation zone 54, 77.22 pound mols per hour through lines 27 and 29 containing 0.05 mol of methane, 0.95 -rnol of ethane, 0.18 mol of propane, 75.6 mols of benzene, and 0.44 mol of ethylbenzene.

The liquid from receiver 18 in the quantity of 558.08 pound mols per hour as described hereinabove is pumped by pump 22 through lines 23, 25 and 26 to an upper region of absorption zone 56. This absorption zone is a gas-liquid contacting zone for recovery of boron triuoride and benzene from the 'gases circulating in the process. 'Ihese gases comprise the separator gas and benzene column overhead gas as set forth hereinabove. The total gas feed to the absorber is in the quantity of 608.45 pound mols per hour and contains 0.15 mol of boron triuoride, 89.4 mols of hydrogen, 71.9 mols of nitrogen, 4.4 mols of carbon monoxide, 268.6 mols of methane, 157.1 mols of ethane, 5.9 mols of propane, and 11.0 mols of benzene. This gas entering absorption zone 56 through line 57 in a lower region of the absorption zone is passed countercurrently to the 558.08 pound mols per hour of recycle benzene supplied through line 26. Recycle rich absorber oil passes from absorption zone 56 through lines 59', 3 and 4 back to reaction zone A 7. This rich absorption oil inthe quantity of 570.7 pound mols per hour has been described hereinabove and contains 0.05 mol per hour of boron tritiuoride which is equal to 331A% of the boron triuoride which is passed as a gas to the absorption zone. There is vented from absorption zone 56, 595.8 pound mols per hour of gas through line 58. This absorption zone 56 is maintained at a temperature of F. or below and at a pressure of 100 p.s.i.g. by means of a pressure control valve, not shown, in vent line 58. The 595.8 pound mols per hour of vent gas from line 58 contains 0.1 mol of -boron triuoride, 89.4 mols of hydrogen, 71.9 mols of nitrogen, 4.4 mols of carbon monoxide, 268.2 mols of methane, 154.7 -mols of ethane, 5.5 mols of propane, and 1.6 mols of benzene.

The ethylbenzene or multiple product column 31 is fed with 101.2 pound mols per hour of benzene column bottoms containing 63.9 mols of ethylbenzene, 7.8 mols of cumene, 20.6 mols of diethylbenzene, 5.1 mols of ethylcumene, 1.5 mols of diisopropylbenzene, 1.9 mols of diethylcumene, and 0.4 mol of triethylcumene. This product column 31 separates overhead the net ethylbenzene and cumene produced. These compounds are separated further into individual components by other fractionation means not shown. This ethylbenzene and cumene product in the quantity of 71.7 mols per hour or 606 barrels per day passes through line 32, is condensed in condenser 33 and passes to overhead receiver 34. From this receiver 34, this product is withdrawn through line 35 by pump 36 which supplies reflux to column 31 through lines 37 and 38. The'net product passes through line 39 to storage or other fractionation means not shown. There is withdrawn through line 39, 69.3 pound mols per hour of ethylbenzene and 7.8 pound mols per hour of cumene.

Recycle, column 41 is fed with 29.5 pound mols per hour' from line 40. This 29.5 pound mols per hour contains 20.6 mols of diethylbenzene, 5.1 mols of ethylcumene, 1.5 mols of diisopropylbenzene, 1.9 mols of diethylcumene, and 0.4 mol of triethylcumene. The function of this column is to separate transalkylatable polyalkyl aromatic hydrocarbons from the more refractory homologs thereof. Thus. V27.2 pound mols per hour ofroolyalkvl aromatic hydrocarbons pass overhead from column 41 through line 42, are condensed in condenser 43 and pass to overhead receiver 44. This 27.2 pound mols per hour contains 20.6 mols of diethvlbenzene, 5.1 mols of ethvlcumene. and 1.5 mols of diisonronvlbenzene. The liouid from overhead receiver 44 is withdrawn therefrom through line 45 bv Dump 46 which snnolies retiux to column 41 through lines 47 and 48. The net oolvalkvl aromatic hvdrocarbons for passage to the transallfvlation reaction zone are withdrawn through line 49 as hereinafter set forth. The bottoms from recvcle column 41 in the nuanttv of 2.3 pound mols perA hour are withdrawn therefrom through line 55. These 2.3 pound mols ner hour contain 1.9 -rnols of diethvlcumene and 0.4 mol of triethvlcumene, and are withdrawn as bottoms from the process.

Transalkvlation reaction zone 54 is fed with 27.2 pound mols per hour of polyalkvl aromatic hydrocarbons through lines 49. 50.and 52. The composition of these oolyalkvl aromatic hydrocarbons has been set forth hereinabove. Tn addition. as set forth hereinabove, there is admixed therewith nrior to passage thereof to this transalkvlation reaction zone 77.22 nound mols oer hour of recvcle benzene through lines 27 and 29. The composition of this 77.22 pound mols per hour has been set forth hereinabove. In addition. there is added through line 51 the net make-11o boron triuoride for the process in the quantity of 0.1 pound mol per hour. In this example, this is the only necessary point of boron trifluoride introduction. The

' combined feed passing through line 52 and heat exchange zone 53 to transalkylation reaction zone 54 is in the quantity of 104.5 pound mols per hour. Transalkylation reaction zonei 54 is maintained at 550 p.s.i.g. and 160 C.

0.75. The 104.5 pound mols per hour-of combined feed passing to lreactor 54 contains 0.1 mol of boron trifluoride, 0.05 mol of methane, 0.95 mol of ethane, 0.18 mol of propane, 75.6 mols of benzene, 0.44 mol of ethylbenzene, 20.6 mols of diethylbenzene, 5.1 mols of ethylcumene, and 1.5 mols of diisopropylbenzene. The benzene to polyalkyl aromatic hydrocarbon ratio is about 2.8:l, and the benzene to alkyl group present in the polyalkyl aromatic hydrocarbon ratio is about'1.4:1.

In reactor 54, the alkyl groups are transferred from the dialkyl benzene hydrocarbons to benzene to form monoalkyl benzene hydrocarbons. The reactor efuent passes from reaction zone 54 through lines 3 and 4 back to alkylation reaction zone 7. This not only provides a means for double utilization of the boron triuoride introduced to the process through line 51, but also helps to maintain the desired benzene to oleiin ratio in alkylation reaction zone 7. The reactor eluent from reaction zone 54 which passes through line 3 is in the quantity of 104.5 pound mols per hour and contains 0.1 mol of boron tritluoride, 0.05 mol of methane, 0.95 mol of ethane, 0.18 mol of propane, 62.1 mols of benzene, 23.5 mols of ethylbenzene, 3.9 mols of cumene, 10.3 mols of diethylbenzene, 2.6 mols of ethylcurnene, and 0.8 mol of diisopropylbenzene.

The mol balances in and out of the 606 barrels per day ethylbenzene and cumene plant are presented .in the following table:

16 TABLE r A lkyl aromatic yield, Mdar: Per- Per- 0n benzenevcent cent 0n ethylenethyl 92. 6 92. 5 Bottoms and loss 7. 5

o Totsl. 100. 0

n o eneum m m Bottoms and loss 22. 8

^ Total 100. 0

From Table I the following yield structure is observed: ethylbenzene yield (molar) on benzene is 86.4%. mene yield on benzene is 10.5%. Yield of monoalkyl aromatic hydrocarbon is 96.9%. Benzene bottoms plus loss are 3.1%. Ethylbenzene yield based on ethylene is 92.5%. Cumene yield on propylene is 77.2%. Thus, high vyields of alkyl-aromatics based on benzene and ole- 1in charged to the process are obtained by `utilization of the process of the present invention. Furthermore, these yields areattained with a net consumption of about 0.1 mol of the boron triuoride catalyst per 71.7 mols of monoalkylbenzene produced or less than one-one hunin the presence of ahigher concentration of boron tri-A tluoride than is maintained in said tirst reaction zone, and

passing EP3-containing eluent from said second zone to said first zone in sufficient quantity to supply said catalytic amount of boron tritiuoride in the lirst zone.

2. 'Ihe process of claim 1 further characterized in that each of said reaction zones contains aluminapacking material.

3. The process of claim 1 further characterized in that said second reaction zone contains from about 0.002 to about 1.2v grams of borontriuoride per gram mol of polyalkylated aromatic hydrocarbon and in that said rst reaction zone contains not more than 0.8 gram of boron trifluoride per gram mol of olefin-acting compound.

4. The process of claim 3 further characterized in that eachtof said `reaction zones contains a boron triuoride modified substantially anhydrous alumina.

5.' The process of claim 1 further characterized in thatk said olefin-acting compound is an olenic hydrocarbon.

6. The process of claim 1 further characterized in that said olen-acting compound is an olenic hydrocarbon and in that the alkylatable aromatic hydrocarbon supplied to each of the reaction zones is benzene.

7. The process of claim 6 further characterized in that said olenic hydrocarbon is ethylene.

8. The process of claim 6 further characterized in that said olenic hydrocarbon is propylene.

9. The process of claim 6 further characterized in that said olenic hydrocarbon is a butene.

10. The process of claim 1 further characterized in that the rst reaction zone is maintained at a temperature of from about 0 to about 300 C. and the second reaction zone is maintained at a higher temperature in the range of from about 150 to about 350 C.

111. A process for the production of an alkyl benzene hydrocarbon which comprises alkylating an alkylatable benzene hydrocarbon with an olen in the lpresence of a catalytic amount of boron triuoride in a first reaction zone containing a boron triuoride modied substantially anhydrous alumina, separating from the resultant reaction zone euent desired alkylated benzene hydrocarbon and higher molecular weight polyalkylated benzene hydrocarbon, subjecting at least a portion of said polyalkylated benzene hydrocarbon in a second reaction zone containing a boron triuoride modified substantially anhydrous alumina to reaction with alkylatable benzene hydrocarbon in the presence of a higher concentration of boron triuoride and at a higher temperature than are maintained in said first reaction zone, and passing BPB-containing efuent from said second zone to said first zone in sucient quantity to supply said catalytic amount of boron triuoride in the rst zone.

References Cited in the le of this patent Lien et al. Sept. 16, 1958 

1. A PROCESS FOR THE PRODUCTION OF AN ALKYL AROMATIC HYDROCARBON WHICH COMPRISES ALKYLATING AN ALKYLATABLE AROMATIC HYDROCARBON WITH AN OLEFIN-ACTING COMPOUND IN THE PRESENCE OF A CATALYTIC AMOUNT OF BORON TRIFLUORIDE IN A FIRST REACTION ZONE, SEPARATING FROM THE RESULTANT REACTION ZONE EFFLUENT DESIRED ALKYLATED AROMATIC HYDROCARBON AND HIGHER MOLECULAR WEIGHT POLYALKYLATED AROMATIC HYDROCARBON, RECOVERING SAID DESIRED ALKYLATED AROMATIC HYDROCARBON, SUBJECTING AT LEAST A PORTION OF SAID POLYALKYLATED AROMATIC HYDROCARBON IN A SECOND REACTION ZONE TO REACTION WITH ALKYLATABLE AROMATIC HYDROCARBON IN THE PRESENCE OF A HIGHER CONCENTRATION OF BORON TRIFLUORIDE THAN IS MAINTAINED IN SAID FIRST REACTION ZONE, AND 